Study on Mitigation of Interfacial Intermetallic Compounds by Applying Alternating Magnetic Field in Laser-Directed Energy Deposition of Ti6Al4V/AA2024 Dissimilar Materials

Abstract

Brittle intermetallic compounds (IMCs) at the interface of dissimilar materials can seriously affect the mechanical properties of the dissimilar components. Introducing external assisted fields in the fabrication of dissimilar components is a potential solution to this problem. In this study, an alternating magnetic field (AMF) was introduced for the first time in the additive manufacturing of Ti6Al4V/AA2024 dissimilar alloy components by laser-directed energy deposition (L-DED). The effect of the AMF on the interfacial IMCs’ distribution was studied. The results indicate that the contents of the IMCs were different for different magnetic flux densities and frequencies, and the lowest content was obtained with a magnetic flux density of 10 mT at a frequency of 40 Hz. When an appropriate AMF was applied, the IMC layer was no longer continuous at the interface, and the thickness was notably decreased. In addition, the influence of the AMF on the temperature distribution and fluid flow in the melt pool was analyzed through numerical simulation. The simulation results indicate that the effect of the AMF on the temperature of the melt pool was not significant, but it changed the flow pattern inside the melt pool. The two vortices inside the cross-section that formed when the AMF was applied caused different orientations of club-shaped IMCs inside the deposition layer. A sudden change in the streamline direction at the bottom of the longitudinal cross-section of the melt pool can affect the formation of the IMC layer at the interface of dissimilar materials, resulting in inconsistent thickness and even gaps. This work provides a useful guidance for regulating IMCs at dissimilar material interfaces.